Generate CircleCI config.yml from a script (#17039)
Summary:
This initial PR splits the `.circleci/config.yml` file into several smaller files that are stitched verbatim back into the original. A proof of concept of dynamically generating yaml for the job configuration list is also introduced.
Since the `config.yml` file must exist in the repo in its final form, there must exist a manual update and check-in step to regenerate `config.yml` from its constituent parts.
Consistency between the checked-in `config.yml` file and the authoritative source data is enforced at build time through TravisCI.
closes #17038
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17039
Reviewed By: yf225
Differential Revision: D14109059
Pulled By: kostmo
fbshipit-source-id: bc04a73145290358854f5a5e552a45e559118fc3
